MOSCOW – Prime Minister Vladimir Putin said Tuesday that Russia wants the U.S. to share detailed data about its planned missile shield under a new arms control treaty, signaling potential new difficulties in the ongoing negotiations between Moscow and Washington.
Putin's televised remarks set a defiant tone as negotiators try to hammer out a successor to the 1991 Strategic Arms Reduction Treaty that expired on Dec. 5. The two countries had hoped to reach a deal before the end of the year, but problems persist.
Putin also said that Russia will build new weapons to offset the U.S. missile defense system.
The U.S. State Department rejected Putin's call, saying the START successor treaty would only deal with strategic offensive arms.
"While the United States has long agreed that there is a relationship between missile offense and defense, we believe the START follow-on agreement is not the appropriate vehicle for addressing it," spokesman Ian Kelly said in Washington.
"We have agreed to continue to discuss the topic of missile defense with Russia in a separate venue," he said.
Putin's comments showed that the former Russian president is continuing to shape Russian foreign policy, which under the constitution should be set by his successor, Dmitry Medvedev.
He said that the arms control talks were proceeding in a positive way and added that Medvedev and President Barack Obama will eventually decide whether to strike an arms deal.
But Putin warned that a missile defense system would give the U.S. an edge and could erode the deterrent value of Russia's nuclear forces.
"The problem is that our American partners are developing missile defenses, and we are not," Putin said.
"But the issues of missile defense and offensive weapons are closely interconnected. ... There could be a danger that having created an umbrella against offensive strike systems, our partners may come to feel completely safe. After the balance is broken, they will do whatever they want and grow more aggressive."
Obama removed a major irritant in relations earlier this year by scrapping the previous administration's plans to place interceptor missiles in Poland and a radar in the Czech Republic — deployments Russia treated as a threat.
The Kremlin has praised Obama for the decision, but Russian officials have also said they want to know more about the sea- and land-based systems the U.S. plans to put in place instead.
Putin said that Russia has no intention to build a missile shield of its own, but will have to develop new offensive weapons to offset a future U.S. missile defense.
"In order to preserve a balance while we aren't planning to build a missile defense of our own, as it's very expensive and its efficiency is not quite clear yet, we have to develop offensive strike systems," he said.
Putin added that the U.S. must share information about their missile defense plans if they want Russia to provide data on its new weapons.
"They should give us all the information about the missile defense, and we will be ready then to provide some information about offensive weapons," Putin said.

U.S. officials have said the negotiations to replace START have become hung up over Russia's opposition to retaining the ban on the encryption of missile flight data. The 1991 treaty banned such encryption so each side could monitor missile tests from a distance and determine whether the other side was developing missiles restricted by the treaty. Russia has little interest in monitoring such data because it is working to upgrade its missile arsenal, while the United States is not testing new missiles.